Water Structure in the Submembrane Region of a Floating Lipid Bilayer: The Effect of an Ion Channel Formation and the Channel Blocker

Abstract

The structure of water in the sub-membrane region of the bilayer of DPhPC floating (fBLM) on a monolayer of 1-thio--D-glucose (-Tg) modified gold nanoparticle film was studied by the surface enhanced infrared absorption spectroscopy (SEIRAS). SEIRAS employs surface enhancement of the mean square electric field of the photon which is acting on a few molecular layers above the film of gold nanoparticles. Therefore, it is uniquely suited to probe water molecules in the submembrane region and provides unique information concerning the structure of the hydrogen bond network of water surrounding the lipid bilayer. The IR spectra indicated that water with a strong hydrogen network is separating the membrane from the gold 2 surface. This water is more ordered than water in the bulk. When alamethicin, a peptide forming ion channels is inserted into the membrane the network is only slightly loosened. The addition of amiloride-an ion channel blocker results in a significant decrease in the amount of water in the sub-membrane region. The remaining water has a significantly distorted hydrogen bonds network. This study provides unique information about the effect of the ion channel on water transport across the bilayer.The electrode potential has a relatively small effect on water structure in the submembrane region. However, the IR studies demonstrated that water is less ordered at positive transmembrane potentials. The present results provide significant insight into the nature of hydration of floating lipid bilayer on the gold electrode surface.

Electrochemical Properties of Lipid Membranes Self-Assembled from Bicelles

“…The minimum of the v(O-H) band is located at ~3225 cm −1 and it contains a visible shoulder at ~3350 cm −1 . The ν(O-H) bands within this spectral region correspond to the water molecules in a network of hydrogen bonds [30][31][32]. Hence, the emergence of the negative ν(O-H) band indicates that the adsorption of bicelles involves the replacement of hydrogen-bonded water from the interfacial region.…”

Ionophore properties of valinomycin in the model bilayer lipid membrane 1. Selectivity towards a cation

“…The water content in the spacer region of tBLM is small [30,31]. In contrast, the water content in the spacer region of fBLM is high [16,32]. Significant differences between the values of Q m for tBLMs with valinomycin in the presence of K + and Na + ions were observed [15].…”

Biomimetic Models to Investigate Membrane Biophysics Affecting Lipid–Protein Interaction

“…Lipid bilayers are separated by a thin water gap from the substrate and the thickness of that water layer depends on the material of the substrate (∼1 nm when using hydrophilic glass). Many researches aimed to suspend the bilayer on polymer or other cushion to avoid such direct interaction or increase that thickness by engineering a floating bilayer membrane (Su et al, 2020). The first study investigating the lipid diffusion (Tamm and McConnell, 1985) in a single SLB was performed using a silicon substrate.…”